Portable disc based streaming devices such as portable audio players or video players are getting more and more widespread. These devices are, when e.g. carried along by its user, battery driven and total playing time before having to recharge or replace the batteries is a crucial feature distinguishing the acceptance of such devices. Total playing time depends directly on the devices' battery life, which again depends on the battery's capacity and the power consumption of the portable storage device. The portable devices are equipped with storage devices, such as a hard disk drive or an optical disk drive for storing the data, such as music clips or video sequences, to be streamed by the portable storage device. These storage devices comprise an electrically driven motor unit mechanically propelling the storage media. This operation is with regard to other units comprised in the portable storage devices a major power consumer responsible for a substantial part of the total dissipated power. In order to minimise power consumption of these storage devices, disk scheduling has been introduced. Hereby, the portable storage device comprises a cache memory and data is transferred from the disk drive to the cache memory and therefrom for further processing, and vice versa. A disk scheduler in the portable streaming device optimises the ratio between standby time and active time of the bit-engine, which is reading data from the storage device. Controlled by the disk scheduler, the storage device is spun down, i.e. the motor unit is switched off, as often and as long as possible by transferring the data to and from the storage medium of the storage device in a burst-like manner. This is achieved by using large scheduling buffers that allow the portable storage device to maximise the standby time between two accesses to the storage medium. A fixed part of the solid state memory totally available in the portable storage device is reserved for this purpose. Often, a dedicated separate hardware comprising memory circuit is arranged in the portable streaming devices as buffer memory. The larger the buffer is, the longer the drive can be switched off and hence the bigger the power savings. Although memory tends to become cheaper over time for the same amount of memory, it is still desirable to minimise the amount of hardware that is reserved for one single application, in the present case disk scheduling buffer, in order to reduce the cost and to increase the performance of portable streaming devices.
Moreover, a further problem associated with the above-described strategy of switching the storage device of the portable streaming device off and on is that the life-time of the storage devices is limited to a certain number of start-stop cycles due to the mechanical part of the storage devices suffering from wearing out. Therefore it is even for this purpose desirable to have an as large as possible buffer in order to decrease the number of start-stop cycles over time and therefore increase life-time of the storage device and thus of the portable streaming device as a whole.